There is an increasing desire to provide automotive vehicles with both a windshield washer and a rear window washer, particularly in vans and sport utility vehicles having a generally vertical rear window. With this trend comes the design challenge of providing an economical means for supplying both rear and forward windows with washer fluid. In the past, separate washer pumps have been used to provide the necessary fluid. However, such a design is uneconomical due to duplication of components providing the same function. While it is known in the art to provide a dual output washer pump to obviate the economic drawbacks of separate pumps, current designs have not sufficiently solved the technical problem of generating two separate fluid flows from a single washer pump due to complexity, lack of function, or both.
One such design is shown in U.S. Pat. No. 4,600,361 (Bianco), which discloses a dual outlet washer pump having a horizontally positioned shutter means for separating and sealing two manifold chambers, and two separate communication conduits 21, 22 extending tangentially from an impeller housing and opening at either manifold chamber. This design is not only complex, requiring separate communication conduits and a hermetic seal between separate manifold chambers, but also lacks functionally due to the tortuous fluid path from the impeller housing, through the communication conduits, vertically upward or downward into a manifold chamber, and a 90.degree. turn into a delivery manifold. Such a path results in pressure losses and adversely affects performance reliability. In addition, only half of the fluid flow from the impeller is channeled into a communication conduit due to the horizontal positioning of the manifold chamber, thus increasing energy requirements for the motor of the pump.
Another dual output pump, shown in French Patent 1,142,593, reveals various embodiments for a flow selector to alternately block one or the other of an outlet from the pump. Some embodiments show a shutter 7 which pivots and thus requires more complex construction, while another embodiment shows a flow selector made of a deformable material which has a separate bowl 11 held at the periphery to block an outlet. The flow selector of the latter embodiment is not only difficult to manufacture due to the addition of the bowl 11 onto the flexible material, but also may not meet the frequent open/shut requirements of the washer pump due to misalignment of the bowl 11 with the outlet.
There is thus needed a dual output washer pump which reliably provides an output stream of washer fluid, which has a simple design, which does not require excessive motor energy, and which is easy to assemble.